Thank you DeWayne, I rolled back to the old nvidia driver 526.86 and turned off GPU Scheduler and all the stutters dissapeared, all of them.
If I open the Task Manager to watch the GPU usage the stutters come back, so I believe it is something related with the GPU or CPU usage causing the stutters.
For now it is fixed for me, but it is really painful having to reconfigure the whole PC setup on every WU or SU.